Re: [PATCH 0/8] Introduce fwctl subystem

Jiri Pirko
2024-06-07T15:50:47Z

Fri, Jun 07, 2024 at 05:14:51PM CEST, jgg@nvidia.com wrote:
>On Fri, Jun 07, 2024 at 08:50:17AM -0600, David Ahern wrote:
>
>> Mellanox offers both with the Spectrum line and should have a pretty
>> good understanding of how many customers deploy with the SDK vs
>> switchdev. Why is that?
>
>We offer lots of options with mlx5 switching too, and switchdev is not
>being selected by customers principally for performance reasons, in my
>view.
>
>The OVS space wants to operate the switch much like a firewall and
>this creates a high rate of database updates and exception
>packets. DPDK can operate all the same offload HW from userspace and
>avoid all the system call and other kernel overhead. It is much more
>purpose built to what OVS wants to do. In the >50Gbps space this
>matters a lot and overall DPDK performance notably wins over switchdev
>for many OVS workloads - even though the high speed path is
>near-identical.
>
>In this role DPDK is effectively a switch SDK, an open source one at
>least.
>
>Sadly I'm seeing signs that proprietary OVS focused SDKs (think
>various P4 offerings and others) are out competing open DPDK on
>merit :(
>
>For whatever reason the market for switching is not strongly motivated
>toward open SDKs, and the available open solutions are struggling a
>bit to compete.
>
>But to repeat again, fwctl is not for dataplane, it is not for
>implementing a switch SDK (go use RDMA if you want to do that). I will

switch sdk is all about control plane.

>write here a commitment to accept patches blocking such usages if
>drivers try to abuse the purpose of the subsystem.
>
>Jason